The term “HVAC system” or “HVAC unit” as used throughout this patent application is to be interpreted as covering a system or unit which at its simplest simply draws air in via the filter and distributes this filtered air to the inside of the cab or a system or unit which additional heats and/or conditions the air which is drawn in via the filter.
Such HVAC systems include a HVAC unit which draws air in from the outside of the cab via an air intake and ducting and deliver processed air to the interior of the cab by further ducting. The HVAC unit may be installed in a number of locations such as in the roof of the cab, below the driver's seat and even below the cab floor. Whilst mounting the HVAC unit in the roof may simplify the ducting connecting the unit to the air intake and the cab it presents problems in delivering air to the desired zones, for example, for de-icing the windscreen of the cab and for heating or cooling the driver as this is difficult to do satisfactorily using air jets directed downwardly from the roof. Also HVAC units mounted on or below the floor are problematical as they require extensive ducting which has sealing and insulating problems and requires expensive tooling for manufacture as well as requiring relatively complex installation procedures.
It is an object of the present invention to provide a tractor cab construction which offer a solution to the above problem of interconnecting the HVAC unit with its outlets into the cab and which also has other installation advantages.
A tractor cab having a floor at least part of which is of a double layer construction having an upper layer and a lower layer spaced vertically below the upper layer to define a cavity therebetween, an HVAC unit supported on the lower layer of the floor with the output of the HVAC unit directed through passages formed between the layers the upper layer including output apertures through which air from the HVAC unit can be discharged or recirculated.
As will be appreciated, a cab with such a floor structure has significant advantages in the connection of air, electrical wiring and/or hydraulic pipes and hoses as well as providing additional storage for fluids or other materials.
In a preferred arrangement the upper layer is generally flat and the lower layer is curved in three dimensions to define passages between the layers along which air and/or wires and/or pipes and/or hoses can extend or volumes in which fluid or other materials and equipment can be stored.
The HVAC unit may be partially recessed into the floor by being supported in a depression formed in the lower layer of a rear portion of the floor and air from the HVAC unit is directed forwardly along passages formed between the layers to air openings formed in a front portion of the floor and/or in side portions of the floor, a support structure being provided above the HVAC unit on which a driver's seat is mounted. Such an arrangement is particularly convenient and provides a seat mounting above the HVAC unit without the seat being too high.
Outlet ducts are preferably connected with the air openings in the front portion of the floor to direct air towards a windscreen of the cab and the front of a driver and ducts are connected with the air openings in the side portions of the floor to direct air towards side windows of the cab and the side of the driver
The floor layers can be formed from metal sheets welded together or from reinforced plastics material which is glued or otherwise secured together.
The invention also provides a tractor cab HVAC system in which HVAC unit is connected with air outlets into the cab via passages formed in a two layer floor as described above.